The Internet is increasingly being used as a distribution medium for entertainment content such as movies, music, or other multi-media presentations. At one time, it was predicted that a user would be able to order digital content (e.g., a movie) over the Internet and have it streamed in real-time to their computer. However, systems having sufficient computing capacity to provide an acceptable level of real-time streaming video performance have proven to be too expensive for most users. Additionally, Internet capacity for providing wide scale delivery of streaming video content is, at this time, insufficient. In order to allow distribution of digital content over the Internet, content providers typically rent the content to end users for a specified time period and allow the end users to store the content upon their personal computers so that they can access the digital content later.
Unfortunately, this system facilitates unauthorized distribution of copies of copyrighted material. For example, a user can easily copy the digital content and inappropriately distribute it over the Internet. This could potentially cause copyright holders to lose revenue. Recent court cases show that the entertainment industry is intent upon preventing unauthorized access and copying of their property. At the same time, they want to facilitate distribution of their content to as wide an audience as possible. Therefore, copyright holders are looking for methods of delivering high quality content over the Internet that still protect their copyright privileges.
Currently, there are two predominant digital content protection models that are used in the distribution of video content (e.g., television programming or movie distribution), conditional access (CA) and digital rights management (DRM). Conditional access (CA) is a technology that is mainly used to control access to digital programming to authorized users by encrypting the transmitted programming. Conditional Access has been used for years for pay-per-view broadcasts of live content (e.g., sports events, etc.) that is encrypted and broadcast to end users and selectively decrypted at the end user's site using a set-top box.
FIG. 1 is a diagram of an exemplary prior art Conditional Access system 100. In FIG. 1, a content provider 101 transmits digital content to end users (e.g., end users 120, 121, 123, and 124 of FIG. 1) via broadcast network 150. The digital content is encrypted at the uplink site (e.g., site 110) using a previously chosen encryption key. Distribution of the keys for decrypting the digital content is typically accomplished by sending smart card storage devices containing the decryption keys to the end users. The smart card is inserted into the end user's set-top box (not shown) and thus enables the end user to decrypt the digital content. For example, the set-top box filters out the broadcast signals and decrypts them using the decryption key stored on the smart card. The decrypted signal is then decoded and output to the end users' television.
Many users may find the CA model inconvenient because of the delay involved in delivering the decryption key to the end user. Furthermore, to deliver streaming content over the Internet, there must be a continuous high bandwidth link between the end user and content provider which may be difficult to maintain for the duration of the content broadcast.
FIG. 2 is a block diagram of an exemplary prior art DRM system 200. DRM technology addresses the need for protecting file distribution. DRM has emerged as a set of technologies and business models to protect digital media copyrights and to provide revenue to content owners. In FIG. 2, repository 210 holds the content offered for distribution by content provider 101. When a user orders a file or other digital content (e.g., a movie) the content is sent from repository 210 to encrypted content server 220. Encrypted content server 220 packages the content for distribution to the end users by encrypting the requested content with a session key that is sent from encrypted content server 220 to license server 230. License server 230 maintains a license file 235 containing the session key and a description of the usage rules associated with the requested content. End user 120 receives encrypted content file 225, which they can store upon their computer, and communication is established with license server 230 to verify access rights to the encrypted content and obtain the session key for decrypting the content file. Once access rights have been verified, end user 120 can access the requested content.
There are a variety of problems associated with the DRM system as described. For example, the license, describing the usage rules associated with the digital content, describes a one-to-one relationship in which a specific piece of digital content can be accessed by a designated playback device during a specified time interval. This is inconvenient for many users who, having more than one television, may wish to access the content using multiple playback devices. Thus, a user may wish to begin watching a piece of digital content (e.g., a movie) in their living room, and finish watching it later in the night in their bedroom on a second television. However, the license associated with the digital content only allows the movie to be played one specific device, for example, the television in the living room, and only within a single specified time period.
Currently, a user wanting to watch the same piece of digital content on multiple television sets is required to obtain multiple licenses for that piece of digital content. Thus, a first license, associated with a first copy of the digital content, is obtained allowing the end user to watch the digital content on the television in their living room. A second license, associated with a second copy of the same digital content, is obtained allowing the end user to watch the digital content in their bedroom. This system is inconvenient to the end users because they have to obtain multiple licensed copies of the content. Additionally, the users have to determine which copy of the digital content can be played upon a given television set. This system is also inconvenient and expensive for the content providers because they need to send multiple copies of the same content to the same user. Thus, the content providers cannot use their bandwidth to serve other end users while the multiple copies are being sent.